I 



224 



NA TURE 



[January 5, 1905 



SEISMOLOGY IN JAPAN. 



UNDER the title of " Recent Seismolosical Investi- 

 ,ijations in Japan," Baron Dairoku Kikuchi, 

 former Minister of Education, lias issued for private 

 circulation only an " address " prepared for the late ex- 



MG. I. -Model of a F 

 by the Earthquake 

 bracing, the use of i 



er's Cottage. Showing the essential points of i 

 .-csligation Committee. The chief points to be ob: 

 straps, and the avoidance of mortices and other cuts ; 



position in St. Louis. When we look at this address, 

 which is a quarto volume of 136 pages filled with 

 illustrations, we feel that its author should have doffed 

 his modesty and called it seismology as developed in 

 Japan. To describe the work more closely, we shall 



not be far from the mark if we 



say it is an epitomised translation 



of a number of publications which 



to Europeans have hitherto been 



cryptogramic. It gives us not only 



a resume of sixteen numbers of the 



publications of the Tokyo Earth- 

 quake Investigation Committee — 



called for short the E. I. C. — 



which have been published in a 



European language, and with 



which we are more or less familiar, 



but there is added an abstract of 



forty-seven numbers or volumes 



published in Chinese idiographs. 



Many seismologists have looked at 



them and wondered what they 



meant. The contents of these 



sixty-three publications have been 



epitomised, mixed, and system- 



atised. 



After an introduction to the 



■" recent " investigations, which 



tell us that the first earthquake re- 

 corded in Japan was in .\.D. 416, 



and reference to various investi- 

 gations made by Europeans in 



Japan, we are introduced to the 



system under which investigations and their results 



have been classified and discussed. 



Under the heading " Statistical " we find data 



relating to the distribution of earthquakes in space 



and time, their relation to meteorological conditions, 



NO. 1836, VOL 71I 



and various phenomena. Earthquakes which have a 

 submarine origin are most frequent in summer, when 

 the level of the Pacific Ocean bordering Japan is 

 higher than in winter. Those originating on the land 

 are most frequent in winter, at w-hich season baro- 

 metric pressure is at a maximum. Out of forty-seven 

 destructive earthquakes which 

 originated beneath the Pacific, 

 twenty-three were accompanied by 

 Isiinami or sea waves, which prob- 

 ably means that on these occasions 

 marked and sudden changes had 

 taken place in the configuration of 

 the sea bed. 



.•\mong the instruments which 

 are described we notice a hori- 

 zontal pendulum the bob of which 

 is controlled by a small inverted 

 pendulum. Although the vertical 

 and horizontal dimensions of this 

 apparatus are each only i metre. 

 Prof. Omori tells us that a period 

 of one minute can be obtained 

 without difficulty. Macroseismic 

 motion is described, and after this 

 reference is made to microseisms 

 or pulsations. These two classes 

 of movement Prof. Omori finds 

 alternate in their frequency, so 

 that when the small movements 

 are at a minimum the larger ones 

 may be expected. This observ- 

 ation, we learn, has enabled him 

 on several occasions to predict 

 within ten or twelve hours the 

 occurrence of an earthquake. 

 The geological investigations which have been made 

 chiefly refer to the survey of volcanoes, which is a 

 work outside that done by the Geological Survey. 



The investigations of relationships that may exist 

 between earthquakes and various physical phenomena 



;Oya Spimnin; .,11,, 



urick building and ( 



lowing the effects of the Mino-Owari Earthquake of : 

 chimney constructed according to European practice. 



which affect or are affected by strain in the earth's 

 crust are particularly interesting. .At present con- 

 tinuous magnetic observations are being made in Japan 

 at five stations, from which, amongst other things, it 

 has been observed that on several occasions magnetic 



